In medicine, instruments such as catheters, probes endoscopes, etc., are introduced into the human or animal body for diagnosis or therapy as well as for the withdrawal of rtissue samples. For example, in the treatment of humans instruments may be introduced into the urethra, the ureter, the cervical canal, the esophagus, the stomach, the small intestine and especially the large intestine, which exhibits cancerous degeneracies or their precursors with particular frequency. Instruments are also frequently introduced also into veins or arteries in order to reach the heart chambers, lung arteries, or the like. Since the necessary instruments are introduced into the body from the outside, injuries to the hollow organs, intestines, vessels, and tissue for example, perforations result.
To achieve a more gentle introduction of a proctoscope for large intestine diagnosis or therapy, attempts have previously been made to attach this instrument to the end of an inner section of an inverted tube. The space between the two tube sections is connected to a source of pressurized fluid, and the inner section of the tube is pushed into the large intestine by the pressure prevailing between the two tube sections. The fluid pressure causes the inner tube section to invert as it carries the proctoscope and at the end of the insertion procedure the proctoscope comes into contact with the intestinal wall. However, the inner tube section in this case rolls out on the intestinal mucous membrane and produces frictional artifacts, which may be the reason why this device has not become important in practice, particularly since the changes caused by the introduction of the device make a diagnostic evaluation of the mucous membrane, etc., difficult.